a. Field of the Invention
The instant disclosure relates generally to ablation electrode assemblies. In particular, the instant disclosure relates to ablation electrode assemblies having a mechanism for irrigating the ablation electrode assemblies and/or targeted tissue areas in a human body. The instant disclosure further relates to irrigated ablation electrode assemblies that include an electrode having at least one radially extending passageway for irrigation fluid. In an embodiment, the instant disclosure further relates to irrigated ablation electrode assemblies that include first and second thermally insulating manifolds that will thermally isolate the ablation electrode from the irrigation fluid.
b. Background Art
Electrophysiology catheters are used in a variety of diagnostic and/or therapeutic medical procedures to diagnose and/or correct conditions such as atrial arrhythmias, including for example, ectopic atrial tachycardia, atrial fibrillation, and atrial flutter. Arrhythmias can create a variety of conditions including irregular heart rates, loss of synchronous atrioventricular contractions and stasis of blood flow in a chamber of a heart which can lead to a variety of symptomatic and asymptomatic ailments and even death.
A medical procedure in which an electrophysiology catheter is used includes a first diagnostic catheter deployed through a patient's vasculature to a patient's heart or a chamber or vein thereof. An electrophysiology catheter that carries one or more electrodes can be used for cardiac mapping or diagnosis, ablation and/or other therapy delivery modes, or both. Once at the intended site, treatment can include radio frequency (RF) ablation, cryoablation, laser ablation, chemical ablation, high-intensity focused ultrasound-based ablation, microwave ablation, etc. An electrophysiology catheter imparts ablative energy to cardiac tissue to create one or more lesions in the cardiac tissue and oftentimes a contiguous or linear and transmural lesion. This lesion disrupts undesirable cardiac activation pathways and thereby limits, corrals, or prevents stray errant conduction signals that can form the basis for arrhythmias.
Because RF ablation can generate significant heat, which if not controlled can result in excessive tissue damages, such as steam pop, tissue charring, and the like, it can be desirable to monitor the temperature of ablation electrode assemblies. It can also be desirable to include a mechanism to irrigate the ablation electrode assemblies and/or targeted areas in a patient's body with biocompatible fluids, such as saline solution. The use of irrigated ablation electrode assemblies can also prevent the formation of soft thrombus and/or blood coagulation, as well as enable deeper and/or greater volume lesions as compared to conventional, non-irrigated catheters at identical power settings.
Typically, there are two classes of catheters incorporating irrigated ablation electrode assemblies: open and closed irrigation catheters. Closed irrigation catheters usually circulate a cooling fluid within an inner cavity of the electrode. Open irrigation catheters usually deliver the cooling fluid through open outlets or openings on the surface of the electrode. Open irrigation catheters use the inner cavity of the electrode, or distal member, as a manifold to distribute saline solution, or other biocompatible irrigation fluids known to those of ordinary skill in the art, to one or more passageways that lead to openings/outlets provided on the surface of the electrode. The saline solution (or other biocompatible irrigation fluid) thus flows directly through the outlets of the passageways onto the electrode or distal member. The direct flow of fluid through the electrode can lower the temperature of the distal end of the electrode during operation, rendering accurate monitoring and control of the ablation more difficult.
Some open irrigation catheters can include a thermally insulating manifold made of a reduced thermally conductive material, such as plastic, for example to enable more accurate monitoring and control of the ablation. Although the use of a thermally insulating manifold made of a reduced thermally conductive material can be beneficial, such a thermally insulating manifold can be generally difficult to manufacture and the resulting structures can cause reliability issues.